100/3 RPG ● 'A percentile RPG on a single page where player characters consist of 3 attributes (Violence, Elegance and Intelligence), a profession, a one-sentenced description of their wishes and weaknesses and two hit points (body and insanity).'

13th Age ● 'This is the home of the 13th Age / Archmage Engine system reference document. It contains all the open content from the 13th Age RPG – the Archmage Engine.'

2013 Open Source Calendar ● 'Featuring all your favourite Open Source Heroes and Heroines, these are some of the people who have done most to exemplify or further the cause of a more open, collaborative or more freedom-conscious approach to working, thinking and licensing.'

A Spark in Fate Core ● 'This is an expansion of the (soon to be) award winning Fate Core, focussing on the process of collaborative world building. It includes some of the concepts found in The Spark RPG and helps you build an engaging setting with a history, fraught with danger and potential for growth.'

Achieving Impossible Things ● 'Six "impossible things": GNU/Linux, Wikipedia, the Creative Commons, the Blender Foundation, Open Hardware, and the OLPC/Sugar project. All created under free licenses for everyone to use, in defiance of our conventional ideas of business economics. Is it magic, coincidence, or just plain common sense at work here?'

Action! System ● "The Action! System Core Rules provide all of the basic rules necessary to create and play a role-playing game. Create adventures and characters based on your favorite movies, TV shows or novels."

Adventurer Conquerer King System ● 'Autarch's Adventurer Conqueror King System fulfills the promise of the original fantasy role-playing game by providing comprehensive, integrated support for play across all levels of a campaign.'

Adventures on Dungeon Planet ● 'Adventures on Dungeon Planet is a science fantasy supplement for the award-winning role-playing game Dungeon World.'

Aerogel.org ● '[A]n encyclopedic reference about aerogels, how-to guides for making aerogels and building a do-it-yourself supercritical dryer, the world's most comprehensive aerogel image gallery, a podcast with the world's leading aerogel scientists, and more.'

Aetherverse ● 'Aetherverse is a tabletop sci-fi wargame that I first published in 2004. The concept of the game was to create a sort of “universal” rules system that players could use to create and play with armies sourced from any of the many miniatures manufacturers on the market. While this had been done before in a generic sense, I designed the system to build armies that had real character rather than just being a collection of numbers.'

Authors Alliance ● 'The Authors Alliance embraces the unprecedented potential digital networks have for the creation and distribution of knowledge and culture. We represent the interests of authors who want to harness this potential to share their creations more broadly in order to serve the public good.'

Autodesk ● 'You can freely borrow from the Autodesk Help, Support and Video libraries to build a new learning experience for anyone with a particular need or interest.'

A Spark in Fate Core ● 'This is an expansion of the (soon to be) award winning Fate Core, focussing on the process of collaborative world building. It includes some of the concepts found in The Spark RPG and helps you build an engaging setting with a history, fraught with danger and potential for growth.'

Abulafia ● A collection of random concept and word generators for story gamers.

Take on Magic Items ● '"Take On Magic Items" is a collection of magic items for Dungeon World, though a clever game master could easily translate these items into the fantasy system of choice, especially systems that encourage rulings not rules.'